1. Field of the Invention
The present invention relates to bearing estimation receiver for an air traffic advisory system such as TCAS or TAS for determining the bearing of an intruder aircraft relative to a protected aircraft. More particularly, the invention is concerned with an apparatus for determining a corrected bearing to compensate for bearing errors caused by intruder signal reflections.
2. Description of the Prior Art
In the field of bearing estimation receivers for air traffic advisory systems, a multi-antenna array located aboard a protected aircraft is used to receive intruder signals from an intruder aircraft in response to interrogations from equipment located aboard the protected aircraft. A signal processing unit coupled with the antenna array processes the antenna signals to determine the intruder bearing relative to the protected aircraft.
Various surfaces on the protected aircraft such as the tail, engine cowlings and other antennas produce reflected intruder signals, which are also received by the antenna array. These reflected intruder signals combine with the signals received directly from the intruder aircraft and cause errors in the intruder bearing as determined by the signal processing unit. Also, imperfections within the antenna itself can result in errors in bearing. As those skilled in the art appreciate, an accurately determined intruder bearing is important for avoiding collisions. Accordingly, the prior art points out the need for a more accurate intruder bearing information for the pilot of a protected aircraft.